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Leigh-Ann Mulcahy QC

Call: 1993 QC: 2009


Leigh-Ann Mulcahy QC is listed by the legal directories as a leading silk in four fields (Professional Negligence, Product Liability, Insurance and Administrative & Public Law). She is also a Deputy High Court Judge a role which she combines with her other practice.

She has been described in the legal directories as follows: “an incredibly good appellate advocate”; “at the top of her field”; "truly brilliant"; “ferociously bright”; "she is an iron fist in a velvet glove"; “she has a great reputation and it's fully deserved”; "first-rate"; “outstanding”; “a fantastic advocate”; “extremely diligent”; formidably intelligent”; “extremely bright and highly organised”; “prodigiously hard-working and possesses both a first-class brain and very sound judgment”; “excellent, thorough...with encyclopaedic knowledge of the case-law”; “charming and relentless in equal measure and she exudes confidence. She never loses sight of the big picture and ensures that clients are well informed and happy at all times”;  tenacious with the opposition” “very knowledgeable”, with “strong attention to detail and picks up complex matters quickly”; "if I had a matter that was being litigated and I knew was going to trial I would use her. She is very good at looking at complicated facts, getting to the heart of them and then arguing your corner for you" and produces “stunning performances" in court.

In addition, she is also considered to be “very user-friendly”, “one of the most approachable QCs” and is praised for her "ease of manner with both peers and clients".

Leigh-Ann has wide advocacy experience at all levels, including the Supreme Court and House of Lords. As well as litigation, she acts as an advocate and arbitrator in commercial and insurance arbitrations. She has succeeded in three cases before the Supreme Court (International Energy Group Ltd v Zurich (2015) and The Employers' Liability Policy Trigger Litigation (2012) arising out of the insurance of asbestos liabilities; The Atomic Veterans Litigation (2012) a group action alleging exposure to ionising radiation during the British nuclear tests in Australia and the South Pacific in the 1950s) and one before the House of Lords (Medcalf v Mardell (2003) relating to wasted costs and barristers’ liability). Recent important cases including acting for insurers in a complex insurance coverage dispute arising out of the PIP Breast Implant Litigation, overturning a high value arbitration award for serious irregularity on behalf of the Home Secretary in Secretary of State for the Home Department v Raytheon Systems Ltd (2015) and enforcing a cross-undertaking in damages against HM Revenue & Customs in Abbey Forwarding Ltd (In Liquidation) v Revenue and Customs Commissioners (2015).

Leigh-Ann has extensive experience of handling group/multi-party litigation and is especially noted for cases involving complex technical or scientific evidence. Leigh-Ann accepts instructions as a mediator (CEDR accredited) and is a Senior Decision-Maker for the Guernsey Financial Services Commission.

She specialises in the following areas of practice:

  • Professional liability (including claims involving solicitors, barristers, accountants, insurance brokers and financial services professionals);
  • Product liability (including commercial products, pharmaceuticals, vaccines, food safety, medical devices, blood and blood products);
  • Insurance and reinsurance, particularly all forms of liability insurance;
  • Commercial litigation, including financial services, commercial fraud and utilities law;
  • Public and constitutional law;
  • Human rights;
  • Mediation;
  • Arbitration.

Leigh-Ann held the appointment of First Counsel to the Welsh Government from 2013 to November 2016. In addition, prior to her appointment to silk, Leigh-Ann held the appointment of Treasury Counsel (A Panel) and since taking silk she has continued to act in cases for the UK Government upon the nomination of the Attorney-General. Over the course of some 20 years, she has acted for a wide range of Government departments and other public bodies on issues including public law, EC law and human rights.

Major cases include:

  • International Energy Group Ltd v Zurich Insurance Plc UK [2015] 2 WLR 1472, a Supreme Court appeal involving employers’ liability insurance. Leigh-Ann represented the successful appellant, Zurich. The case concerned asbestos/mesothelioma risks and in particular whether an insurer has any right of contribution from another insurer and/or a right of recoupment from a solvent employer in respect of uninsured periods;
  • The PIP Breast Implant Litigation insurance dispute (2014-15). Leigh-Ann represented RSA on an insurance coverage dispute with Spire Healthcare, a dispute which settled prior to trial.
  • Secretary of State for the Home Department v Raytheon Systems Ltd [2015] 1 Lloyd’s Rep 493 and also [2014] EWHC 4375, TCC (two judgments), an arbitration appeal in which Leigh-Ann acted for the Home Secretary and succeeded in overturning a high value arbitration award for serious irregularity.
  • Abbey Forwarding (in Liquidation) v Revenue and Customs Commissioners [2015] EWHC 225 (Ch); [2015] Bus LR 882. Leigh-Ann represented an insolvent company and succeeded in enforcing a cross-undertaking in damages given by HMRC when seeking an order appointing a provisional liquidator of the company. She is currently acting on the damages Inquiry.
  • Welsh Ministers v Servier (2015). Leigh-Ann is currently acting for the Welsh Claimants in competition law proceedings in the Chancery Division, concerning the supply of the ACE inhibitor, Perindopril.
  • Welsh Ministers v Reckitt-Benckiser (2014). Leigh-Ann acted for the Welsh Claimants in a competition law follow-on claim in the Chancery Division concerning the supply of Gaviscon.
  • Durrheim v Ministry of Defence [2014] EWHC 1960, QB, an appeal to the High Court arising out of an application for conjoined case management of claims for noise induced hearing loss raising issues of combat immunity.
  • Abdale & ors v Ministry of Defence (2014). Leigh-Ann appeared for the Ministry of Defence on a two week hearing before the Upper Tribunal of a set of 12 conjoined appeals which was the first major case testing the legislation governing the war pensions jurisdiction.
  • Davidson v Aegis Defence Services (BVI) Ltd  [2014] 2 All ER 216, a limitation appeal to the Court of Appeal raising novel issues under s.33 Limitation Act 1980.
  • The Employers’ Liability Insurance Trigger Litigation (Durham v BAI (Run Off) Ltd [2012] 1 WLR 867), a multi-party action and major liability insurance case concerning asbestos/mesothelioma risks, which was appealed to the Supreme Court. Leigh-Ann represented Zurich Insurance Company which was successful in its appeal.
  • The Atomic Veterans Litigation (AB & ors v Ministry of Defence [2013] 1 AC 78), a Supreme Court appeal arising out of a large multi-party action arising out of the British nuclear tests in Australia and the South Pacific in the 1950s.  Leigh-Ann represented the Ministry of Defence which succeeded in its limitation defence.
  • The Miners' Knee Litigation (Davies v Secretary of State for Energy and Climate Change [2012] EWCA Civ 1380), a large group action arising out of the development of osteoarthritis in the knee from coal mining. She represented the Department for Energy and Climate Change in successfully resisting an appeal by the claimants to the Court of Appeal.
  • The Porton Down Litigation, a multi-party action arising out of a programme of non-therapeutic experimentation at Porton Down with chemical warfare agents and antidotes. She represented the Ministry of Defence.
  • Medcalf v Mardell [2003] 1 AC 120, a professional liability claim involving the first and only wasted costs case to be heard by the House of Lords. Leigh-Ann appeared on behalf of the successful barrister respondents. As junior counsel, she presented part of the appeal orally before the House of Lords.
  • The BSE Litigation, a multi-party action which arose out of the development of BSE/vCJD and resulted in an ex gratia compensation scheme being set up by the Government. Leigh-Ann acted for the Department of Health and Department of Environment, Food and Rural Affairs. During 2010, she defended a major judicial review of the vCJD Compensation Scheme on behalf of the Department of Health ((2010) Med LR 204 & [2010] EWHC 1225).
  • Aspirin/Reyes Syndrome [2002] Lloyd’s Rep Med 333, a product liability claim in which Leigh-Ann acted on behalf of the Committee on the Safety of Medicines.
  • The Creutzfeldt-Jakob Disease/Human Growth Hormone Litigation, a multi-party product liability action by claimants who had developed CJD as a result of taking human growth hormone or had received the medicine but were “worried well” ((2000) 54 BMLR 1, 79, 85, 95, 100, 103, 104, 111; [2000] Lloyd’s Rep Med 161). Leigh-Ann acted for the Department of Health and Medical Research Council.

She is Consultant Editor and contributor to The Law and Regulation of Medicines (OUP), Editor of Jackson & Powell on Professional Liability (6th and 7th eds) (Thomson Reuters), contributor to R. Goldberg’s Perspectives on Causation (Hart) and General Editor of Human Rights and Civil Practice (OUP). She is also on the Editorial Board of Lexis’ PSL Arbitration.

Leigh-Ann is a non-executive director of Bar Mutual Indemnity Fund Ltd. She is called to the Bar of the Republic of Ireland. She is also an international advanced advocacy trainer.


M.A. (Cantab.) LL.M. (Osgoode, Canada) Dip. E.C.Law (Kings). Scholarships/prizes: Foundation Scholarship (Jesus College); Squire Scholarship (Cambridge University); C.J. Hamson Prize for Contract Law (Cambridge University); Major Scholarship (Inner Temple); Commonwealth Scholarship.